I. Field of the Invention
The present invention relates generally to the field of probes for detecting the presence of insulating material when filling the hollow walls of a building with insulating material.
II. Description of the Prior Art and Prior Art Statement
U.S. Pats. No. 1,055,099; No. 1,661,995; No. 3,680,579; No. 3,817,274; No. 3,048,037; and No. 3,374,764 constitute the closest prior art the inventor has been able to discover relating to the present invention. All of the above-named patents disclose a means for measuring a liquid level. Each of the above level detecting devices is a permanent installation of a measuring device used to measure the liquid level in a tank or the bottom of a ship.
U.S. Pat. No. 3,048,037 constitutes the closest art to the present invention the inventor has discovered. U.S. Pat. No. 3,048,037 discloses a device for measuring the difference in hydrostatic pressure between the top of the liquid in a tank and the bottom of the tank and relating this hydrostatic pressure difference to a liquid level. The device is not portable and the only relationship of this device to the present invention would be the use of pressure to detect the presence of the insulating material in the present invention and the use of a pressure differential to determine a liquid level in the case of U.S. Pat. No. 3,048,037.